  
public class RubberDuck implements Quackable
{
	Observable observable;
	
	public RubberDuck()
	{
		observable = new Observable(this);
	}
	
	public void	quack()
	{
		System.out.println("Squeak");
		notifyObservers();
	}

	public void registerObserver(Observer observer)
	{
		observable.registerObserver(observer);
	}
	
	public void notifyObservers()
	{
		observable.notifyObservers();
	}
}
